Low-sulphur fuel legislation reduce emissions

Paul Boughton
A raft of new legislation is requiring ship owners and operators to change to low sulphur fuels to reduce emissions. Lower sulphur fuels are less viscous than traditional cheaper, heavier fuels. Therefore, pumps and meters must be able to function accurately with lower lubrication and viscosity levels than with more viscous fuels.

As a result, shipping operators are turning to diesel engines equipped with electronic fuel management systems fitted with KRAL Volumeter technology.

Designed to limit sulphur emissions and the resultant cost to the environment due to acid rain, new legislation is currently being phased in both in North America and Europe. The legislation requires marine engines of ocean going vessels to be run on low sulphur fuel.

Californian law already requires that ocean-going vessels marine diesel oil must contain 0.5 per cent sulphur. This is set to be reduced further in January 2012 to 0.1 per cent. The legislation will be applied to all US coastal waters by 2012.

In the North Sea and the Baltic the European Union maximum of 1.5 per cent by mass sulphur content was reduced to 0.1 per cent in January 2010 for vessels berthing in EU waters. Owners and operators of ocean going vessels worldwide will need to comply with this legislation or face huge fines and possible imprisonment. Undoubtedly the limits will get tougher.

Low sulphur fuel (designated DMZ) that meets the requirements of the new legislation is available but it is more expensive than higher sulphur alternatives. It is important for operators to be able to accurately measure fuel consumption in order to keep costs down. Fuel consumption reduction by accurate measurement and moderation of speed will help.

In addition, the minimum viscosity of low sulphur fuels will be 3 centistokes @ 40°C and 2 centistokes at the injector. Low sulphur fuel is less viscous and therefore harder to measure than higher sulphur fuels.

Litre Meter, a manufacturer and supplier of custom flow meters, utilises the helical screw engineered and supplied by KRAL in its range of positive displacement flow meters. Kral helical screw meters are designed to measure accurately at low viscosities.

These meters can be constructed in a variety of materials ranging from low-cost aluminium to 316L stainless steel. These serve almost all metering or flow control applications of viscous fluids. KRAL meters measure flow to an accuracy of between ± 0.1 per cent and ± 0.4 per cent.

The basic meter, produced by KRAL of Austria, is derived from a range of screw pumps that has been widely used for over 50 years. The unit is supplied with the Litre Meter standard or intrinsically safe pick-up and pulse output transmitter system.

A positive displacement meter works by dividing the flow into discrete 'pockets'. This prevents the flow by-passing the meter’s rotor and producing errors. The helical screw flowmeter has rotor scrolls which accept and release continuous flow. While the flow is being transported through the centre portion of the meter it is trapped by the 'flights' of the scrolls, which form positive displacement 'pockets'. A sensor detects the motion of the rotor and produces a high resolution pulse output.

The flow rate range of KRAL’s OM series of meters is between 0.015 and 7,500 l/min. The meters are supplied in sizes from 13 mm (1/2") to 150 mm (6") with BSP screwed entries or DIN flanges. Special connections to customers’ requirements are available.

For more information, visit www.litremeter.com 

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